Reaction curable composition and solid surface material

ABSTRACT

Acrylic compositions filled with alumina trihydrate with the mixed ester reaction product of propylene glycol methacrylate and phosphorus pentoxide have superior mechanical properties and ease of manufacture. In such acrylic compositions, the ester reaction product imparts superior properties by acting as a very effective coupling agent between the alumina trihydrate filler and the acrylic matrix.

BACKGROUND OF THE INVENTION

The present invention relates to filled acrylic solid surface materials.More particularly, it relates to such materials having effectivecoupling between the filler and the acrylic matrix.

Various patents teach different things in relation to the desirabilityand means for achieving coupling between filler and matrix in filledacrylic solid surface materials.

U.S. Pat. No. 4,251,576--Osborn, et al. (1981), teaches the use ofsilanes for tight coupling, and WO 89/05310--Frank, et al. (1989)teaches other silanes useful for loose coupling on the theory that thefillers act as crack propagation enhancers, so that partially decouplingthe particle from the matrix can have the effect of quenching incipientcrack propagation. Although silane coupling agents can be useful inmechanical property enhancement in such products, they can also resultin whitening in the presence of water with temperature cycling. Thesedocuments are incorporated by reference herein for their disclosures ofart-recognized ways to operate in the field of this invention.

Different phosphate esters known as "Zelec" materials from DuPont wereused in filled acrylics in U.S. Pat. No. 3,847,865--Duggins (1974).

U.S. Pat. No. 5,079,279--Hayashi, et al. (1992) proposes the use ofcertain mixed mono- and di-ethyl esters of phosphoric acid to improvestrength in various filled polymers, including in acrylic matrices. Theresulting high molecular weights of the reaction curable mixes and otherproperties causes difficulties in de-areating, filling molds, pouring,pumping and line pressure.

It is desirable to improve such filled polymeric systems using moreeffective additives.

European Patent 449,456--Three Bond Co., Ltd. (1991) discloses aphosphate coupling agent used in the present invention, but fordifferent uses including cyanoacrylate adhesives.

SUMMARY OF THE INVENTION

The present invention provides a reaction curable resin compositioncomprising a curable component, a polymerization initiator for curingthe curable component, an inorganic filler such as alumina trihydrateand a phosphoric acid ester of methacrylic or acrylic acid having theformula:

     CH.sub.2 ═C(R.sub.1)--COO(CH(R.sub.2)CH(R.sub.3)O)n!y--PO(OH)x

where R₁ =H or CH₃ ; R₂ =H or CH₃ ; R₃ =CH₃ or H; R₂ is not the same asR₃ ; n is 2 to 8; x is 1 or 2, and x+y=3. This accounts for a randomnessof the propylene glycol being in head to head or head to tailconfigurations. Preferably n is 3 to 7, most preferably averaging 5.

DETAILED DESCRIPTION

Filled acrylic articles of the invention contain 20-80% by weight ofalumina trihydrate (ATH), preferably 35-70%, sometimes more preferablyabout 65%, and other fillers and adjuvants can be present such ascalcium carbonate. Compositions for casting preferably includeinitiators and syrup of about 20% polymethyl methacrylate (PMMA)dissolved in methyl methacrylate, as is known in the art. Parts,proportions and percentages herein are by weight, except where indicatedotherwise.

Phosphoric acid esters of hydroxy containing methacrylates, acrylatesand other vinylic compounds yield a mixture of phosphate acid esters(mono and di) that are very effective coupling agents in filled vinyl(acrylic) systems. Significantly improved mechanical properties such asflexural, and tensile properties, fatigue resistance, boiling waterstability, impact resistance, hot/cold water cycling whiteningresistance, and thermally induced stress crack resistance, are realizedwith the addition of these esters. Scanning electron micrographs offractured surfaces show filler coupling, and as little as 0.2 parts perhundred parts of filler show improved properties. The phosphate estersare added "neat", in-situ to casting slurries of filler (e.g. aluminatrihydrate or ATH) and liquid syrups (e.g. 20% polymethyl methacrylatein methyl methacrylate monomer) and in curing agents, using peroxide orazo initiation, resulting in well dispersed low viscosity fluids thatyield flaw free castings with enhanced properties. The addition of thesephosphate esters acts immediately compared to silane coupling agentswhich require pre-hydrolysis or considerable time and elevatedtemperature in mixes to be effective. Also, the examples of U.S. Pat.No. 5,079,279 require preheating and extended mixing beforepolymerization.

The following examples demonstrate the coupling activity of selectexamples of phosphate acid esters as measured by the increased flextoughness of the resulting castings.

The phosphate acid esters used are:

A. Mixed esters from reaction of polypropylene glycol methacrylate(average polypropylene oxide segment of 5) such as Sartomer 604, fromSartomer Co. and phosphorus pentoxide.

B. Mixed (mono and di) esters from the reaction of polyethylene glycolmethacrylate (average ethylene oxide segments of 6-7) such as Blemmer Pe350, from Nippon Oils and Fats Co. Ltd. and phosphorus pentoxide.

C. Mixed esters from reaction of polyethylene glycol methacrylate(average ethylene oxide segments 5) such as Sipomer HEM-5 fromRhone-Poulenc and phosphorus pentoxide.

D. Mixed mono-and-di-ethylene esters of U.S. Pat. No. 5,079,279.

Examples 9, 10 and 11 show how to make and use certain of these esters.

Mixes containing ATH syrup, phosphate ester, PMA and water are mixed atroom temperature for 10 minutes.

The mix in a resin kettle is then evacuated of entrapped and dissolvedair at 25 mm of mercury, and while under vacuum the hydroxide slurry isinjected through a septum into the mix. When mix temperature reaches 30°C. with heat from mechanical mixing the GDMA (glycoldimarcapto acetate)is introduced as shown in Table 1 after 30 seconds, the vacuum is brokenand the mix is transferred from the resin kettle to a mold or form. Theroom temperature initiator system begins reacting and a peak temperatureof approximately 128° C. is reached in approximately 9 minutes. Thecured solid casting is allowed to cool slowly in the mold for 5 minutesand then is removed from the mold. The casting is then cooled to roomtemperature. The castings, which are free of flaws and have excellentsurface textures, are cut into blank rods which are then milled to givethin rods. 6

The following examples and tables illustrate the invention.

                  TABLE 1                                                         ______________________________________                                        Examples 1 to 3 and Comparison 1                                              Compositions                                                                  (phosphate acid ester concentration 0.48 parts per                            100 parts filler)                                                                                        Comparative                                                     Examples      Test                                                            1     2       3       1                                          ______________________________________                                        Alumina Trihydrate (ATH)                                                                     620     620     620   620                                      (from Alcan, particle                                                         size 40 μm)                                                                Syrup (20% PMMA in MMA)                                                                      365.3   365.3   365.3 365.3                                    Phosphate acid ester                                                          A              3.01    --      --    --                                       B              --      3.01    --    --                                       C              --      --      3.01  --                                       t-butylperoxy maleic acid                                                                    8.46    8.46    8.46  8.46                                     (PMA)                                                                         Water          0.76    0.76    0.76  0.76                                     Calcium Hydroxide slurry                                                                     4.21    4.21    4.21  4.21                                     (34% in syrup)                                                                Glycoldimercapto acetate                                                                     1.32    1.32    1.32  1.32                                     (GDMA)                                                                        ______________________________________                                    

Table 2 summarizes flexural properties per ASTM D-790 giving the resultsof Examples 1 to 3 and Comparison 1.

                  TABLE 2                                                         ______________________________________                                        Flex Properties                                                                            Examples      Comparison                                                      1     2       3       1                                          ______________________________________                                        Flex Stress (Kg(f)/sq.mm)                                                                    8.13    8.25    8.17  6.88                                     Flex modules (Kg(f)/sq.mm)                                                                   971     972     977   985                                      Work to break (J)                                                                            0.435   0.459   0.455 0.287                                    Strain (%)     1.039   1.076   1.076 0.831                                    ______________________________________                                    

The above table shows improved toughness of over 50% in work to breakfor Examples 1 to 3 over Comparison 1, thus demonstrating couplingactivity. Scanning election micrographs confirm coupling.

The following example and comparisons show coupling activity ofphosphate acid esters in smaller particle size ATH, (8 micron) and thecomparison of its activity to silane coupling.

                  TABLE 3                                                         ______________________________________                                        Example 4 and Comparisons 2 and 3                                                        Example Comparison Comparison                                                 4       2          3                                               ______________________________________                                        ATH (Solem OE431)                                                                          620       620        --                                          ATH (Solem OE431                                                                           --        --         620                                         coated with silane)                                                           Syrup        365.3     365.3      365.3                                       Phosphate acid ester A                                                                     3.01      --         --                                          PMA          8.46      8.46       8.46                                        Water        0.76      0.76       0.76                                        Calcium Hydroxide                                                                          4.21      4.21       4.21                                        GDMA         1.32      1.32       1.32                                        ______________________________________                                    

The flex properties of articles cast from the above compositions aresummarized in Table 4.

                  TABLE 4                                                         ______________________________________                                        Flex Properties                                                                              Example   Comparison                                                                              Comparison                                 Property       4         2         3                                          ______________________________________                                        Flex stress (Kg(f)/sq.mm)                                                                    9.78      8.76      9.56                                       Flex modules (Kg(f)/sq.mm)                                                                   1,002     988       1,040                                      Work to break (J)                                                                            0.580     0.434     0.505                                      Strain         1.160     0.996     1.116                                      ______________________________________                                    

Example 4 using the phosphate acid ester of the invention shows over 33%increased work to break over the control, Comparison 2, and an 8%improvement over Comparison 3 which is silane coated.

Effects of phosphate acid ester concentration on flex properties areshown in Table 5.

These compositions have the same ATH, syrups, PMA, water, calciumhydroxide and GDMA content as examples 1 and 2.

This series has varying amounts of phosphate acid ester A.

                  TABLE 5                                                         ______________________________________                                        Composition and Flex Properties                                               Examples 5-7 and Comparison 4                                                              Examples      Comparison                                                      5     6       7       4                                          ______________________________________                                        Phosphate Ester A                                                                            2.01    3.00    4.00  --                                       Flex stress (Kg(f)/sq.mm)                                                                    8.2     8.2     8.16  6.85                                     Flex Modules (Kg(f)/sq.mm)                                                                   979     979     988   982                                      Work to break (J)                                                                            0.455   0.463   0.455 0.281                                    Strain         1.074   1.096   1.081 0.822                                    ______________________________________                                    

This shows that as little as 0.32 parts of phosphate acid ester (example5) per 100 parts ATH shows enhanced activity.

Comparisons 5 and 6 show the effect of phosphate acid ester activity incalcium carbonate filled acrylic. The amount and ingredients are thesame as examples 1 to 4 except that calcium carbonate is used in placeof ATH, and the phosphate ester is as indicated.

                  TABLE 6                                                         ______________________________________                                        Composition and Flex Properties                                               Comparison 5 and 6                                                                              5     6                                                     ______________________________________                                        Phosphate ester A   --      3.0                                               Flex Stress (Kg(f)/sq.mm)                                                                         8.60    10.68                                             Flex modules (Kg(f)/sq.mm)                                                                        997     976                                               Work to break (J)   0.423   0.716                                             % Strain            0.986   1.326                                             ______________________________________                                    

Table 7 shows the dispersant activity of phosphate acid ester A in ATHsyrup slurries. Viscosities are for Example 1 and Comparison 1 prior toaddition of calcium hydroxide and GDMA accelerators (i.e. with ATH,syrup, water, PMA slurries).

                  TABLE 7                                                         ______________________________________                                        Viscosity Measurements                                                        With and Without Ester                                                        Viscosity (Pascal Sec.)                                                       (Brookfield Model DV-2, Spindle #4)                                                     6 RPM 12 RPM    30 RPM  60 RPM                                      ______________________________________                                        Example 1   1.2     1.20      1.06  9.22                                      Comparison 1                                                                              3.0     2.35      1.69  1.31                                      ______________________________________                                    

Example 6 and 7 and Comparisons 9 and 10 show the decreased viscosity attwo diffrent speeds each from using the pentabutyl phosphate acid esterA versus a different phosphate acid ester D based on a diethylcomposition having the structure: ##STR1##

The formulae for each set of tests had 650 g ATH, 332.7 g of 20% PMMAsyrup, and 3.73 g EDMA. The viscosity tests were done on a BrookfieldModel DV-2 Viscometer with a #4 Spindle, at the indicated RPM, for 1minute. The results are given in Table 8. The ester concentration isgiven both in grams and in parts per hundred filler (pphf).

                  TABLE 8                                                         ______________________________________                                        Viscosity Measurements                                                        With Ester A of Invention and                                                 Ester D Outside the Invention                                                                                      Viscosity                                Example Ester A     Ester D     RPM  (Pascal Sec                              ______________________________________                                        7       1.95 g (0.30 pphf)      30   1.460                                    7       1.95 g (0.30 pphf)      60   1.180                                    8       3.25 g (0.50 pphf)      30   1.570                                    8       3.25 g (0.50 pphf)      60   1.270                                    Comparison          1.95 (0.30 pphf)                                                                          30   2.540                                                        1.95 (0.30 pphf)                                                                          60   1.800                                                        3.25 (0.50 pphf)                                                                          30   3.101                                                        3.25 (0.50 pphf)                                                                          60   2.100                                    ______________________________________                                    

Examples 9 through 11 describe processes of making phosphate esters usedin the invention.

EXAMPLE 9

To 730 gm (1.97 moles) of Sartomer SR604 resin and 0.2 gm of 70%phosphorous acid was added 100 gm (0.70 moles) of phosphoric anhyrideover 3-4 hrs in a 2 liter resin flask under an air atmosphere. Agitationand cooling were used to maintain a temperature of 30°-40° C. Themixture was stirred one hour and then heated to 45° C. (with stirring)for 12 hours. To the resulting acid phosphate was added 14 gm (0.81moles) of water to convert the pyrophosphate esters to the preferredmonoester. The hydrolysis step normally is for 4-12 hours at 60° C.However, hydrolysis continues with storage at ambient temperatures. Thenabout 1,000 ppm of an polymerization inhibitor is added, such asp-methoxyphenol. The product, about 844 gm., is a light to golden yellowliquid.

EXAMPLE 10

To 357 gm (1.02 moles) of Blemmer Pe 350 from Nippon Oil & Fats Co. wasadded 50 gm (0.35 moles) of phosphoric anhyride slowly in an airatmosphere keeping the temperature under 40° C. The mixture was thenstirred for 2-3 hours at 40° C. to allow all the phosphoric anhydride toreact. The 400 gm of dark, almost black, liquid product had an acidnumber of 145 and was tested in filled acrylic products.

EXAMPLE 11

To 156 gm (0.51 moles) of Rhone-Poulenc's Sipomer HEM-5 was added 25 gm(0.18 moles) of phosphoric anhyride slowly in an air atmosphere keepingthe temperature near 30° C. The mixture was then stirred for 5.5 hoursat 50° C. to allow all the phosphoric anhydride to react. The 180 gm oflight brownish-orange liquid product had an acid number of 145.

Results of Examples 10 and 11

The physical benefits of Examples 10 and 11 were seen when added to thefilled acrylic products. There exists a difference between thehydrophobic/hydrophilic character of the ethylene oxide and propyleneoxide adducts with Example 9 being more hydrophobic (mainly waterinsoluble as pure component). Thus, there may be advantages of oneadduct versus the other in applications properties as well as waterabsorption character of the final filled-polymeric composition.

We claim:
 1. A reaction curable resin composition comprising a curablecomponent, a polymerization initiator for curing the curable component,an inorganic filler including alumina trihydrate and a phosphoric acidester of methacrylic or acrylic acid having the formula:

     CH.sub.2 ═C(R.sub.1)--COO(CH(R.sub.2)CH(R.sub.3)O)n!y--PO(OH)x

where R₁ =H or CH₃ ; R₂ =H or CH₃ ; R₃ =CH₃ or H; R₂ is not the same asR₃ ; n is 2 to 8; x is 1 or 2, and x+y=3.
 2. The composition of claim 1wherein R₁ and R₂ each are CH₃.
 3. The composition of claim 2 where in naverages
 5. 4. The composition according to claim 1, wherein thephosphoric acid ester is in an amount of from 0.1 to 0.48% by weightrelative to the inorganic filler.
 5. The composition according to claim1, wherein the inorganic filler is at least one member selected from thegroup consisting of alumina trihydrate, magnesium hydroxide, calciumcarbonate and silica.
 6. The compositions of claim 1, wherein n averages5, R₁ and R₂ each are CH₃, the inorganic filler is alumina trihydrate,and the phosphoric acid ester is in an amount of 0.1 to 0.48% by weightrelative to the inorganic filler.
 7. An artificial marble obtained bymolding and curing the composition according to claim
 1. 8. A process ofcuring a resin composition by mixing the ingredients of claim 1 andpermitting it to react.